PubMed Health⌕ Search

Biomedical subjects

M Lucas

Publications and source records attributed to M Lucas.

At least 73 records · Page 4Linked to original sources
PubMed2000

Limitations in the use of median frequency for lung sound analysis.

The aim of this paper is to investigate methods of standardizing lung sound analysis, with a view to supplementing traditional spirometric air flow measurements to help in the diagnosis of asthma and to provide a measure of the effectiveness of treatment. Lung sounds were measured in nine patients with asthma and five control subjects, alongside air flow measurements of forced expiratory volume (FEV1) and forced vital capacity (FVC). The patients were administered the bronchodilator, salbutamol, to assess how effective these measurement techniques were for quantifying its effect. The results agree with previous studies, that analysis of lung sounds is a potentially useful tool for indicating air flow changes. The results, however, also demonstrate that the emerging standard of 'F50' or 'median frequency' should be treated with great caution because of its high sensitivity to the measurement frequency range. F50 is very unlikely to provide a reliable single indicator of lung condition.

Adolescent↗
PubMed2000

Reduction of severe gingival overgrowth in a kidney transplant patient by replacing cyclosporin A with tacrolimus.

Side effects of certain drugs such as cyclosporin A (CsA) and phenytoin may induce gingival overgrowth which in some instances become unacceptable to the patient because esthetic, functional, and other effects. Use of these drugs is related to important medical situations, such as organ transplantation and control and withdrawal of the drugs is contraindicated. Tacrolimus is an immunosuppressant used to prevent graft rejection in organ transplant patients and has been shown to cause fewer oral side effects than CsA. This report deals with a case of probable synergism between the use of CsA and phenytoin which caused an intense gingival overgrowth in a kidney transplant patient. A treatment protocol including very thorough oral hygiene, scaling and root planing, clorhexidine digluconate rinses (0.12%), and substituting CsA with tacrolimus is described. Response to treatment after 6 months of tacrolimus use was excellent with almost complete reversion of the gingival enlargement. One-year follow-up demonstrated a stable gingival situation. The successful substitution of CsA with tacrolimus provides great expectations for the management of CsA-related gingival enlargement.

Anticonvulsants↗
PubMed2000

Semantic priming without association: a meta-analytic review.

A meta-analysis of 26 studies indicated that automatic semantic priming can occur without association. Priming did not vary substantially with differences in variables that affect automatic versus strategic processing, such as time spent processing the prime and target, relationship proportion, and task (except that average effects were smaller in the naming task). Although category coordinates were investigated in the majority of studies, synonyms, antonyms, and script relations also demonstrated priming; functional relations showed greater priming, and essential and perceptual relations showed less. The average effect size for semantic priming was smaller than that for associative priming, suggesting that there is an "associative boost" from adding an associative relationship to a semantic one. The implications of these findings for the modularity thesis and for models of semantic priming are discussed.

Adult↗
PubMed1999

Microalbuminuria as renal marker in recurrent acute tonsillitis and tonsillar hypertrophy in children.

Raised levels of microalbuminuria pointing out glomerular abnormality and indicate renal damage. Glomerulonephritis is caused by immune reaction leading to the formation of circulating immune complexes that are deposited on the basal membrane of the glomerulus. The time course and the appearance of antibodies against infectious agents both play very important roles in its clinical presentation. Antibodies against streptococci have not a protective role, but offers a useful marker of the presence or absence of recent infection. This work studies the presence of microalbuminuria and circulating anti-streptococcal antibodies, namely, anti-streptolysin O and anti-deoxyribonuclease B antibodies in ninety children which underwent tonsillectomy due to infectious and obstructive tonsillar pathology. These children were divided in recurrent acute tonsillitis (n= 34), recurrent tonsillitis with tonsillar hypertrophy (n = 26), and tonsillar hypertrophy (n = 30). It was found in recurrent acute tonsillitis a moderate correlation between microalbuminuria and anti-streptolysin O, and a weak correlation between microalbuminuria and anti-deoxyribonuclease B antibodies. It was also found significant differences of the levels of anti-streptococcal antibodies between the three groups of pathologies. It is proposed the determination of microalbuminuria, an inexpensive and harmless test, as an indicator of possible renal damage in recurrent acute tonsillitis.

Acute Disease↗
PubMed1999

Safety profile of ultrasmall superparamagnetic iron oxide ferumoxtran-10: phase II clinical trial data.

The safety data from the phase II clinical trial of ferumoxtran-10, an ultrasmall superparamagnetic iron oxide contrast agent, are presented. One hundred and four patients with focal liver or spleen pathologies underwent ferumoxtran-10-enhanced magnetic resonance (MR) imaging at doses of 0.8, 1.1, and 1.7 mg Fe/kg. Overall, 15% patients reported a total of 33 adverse events, regardless of causality. The adverse events most frequently seen were dyspnea (3.8%), chest pain (2.9%), and rash (2.9%). No serious adverse events were reported during the 48 hour observation period. There were no clinically significant effects on vital signs, physical examination, and laboratory results. Ferumoxtran-10 is a safe and well tolerated MR contrast agent.

Contrast Media↗
PubMed1999

Lack of lymphoid cell apoptosis in the pathogenesis of tonsillar hypertrophy as compared to recurrent tonsillitis.

UNLABELLED: The pathogenic mechanism of tonsillar hypertrophy is unknown and lacks a proper infectious or immunological explanation. Epidemiological studies point to polluted environments as the main cause of tonsillar hypertrophy in the adaptation of the juvenile organism. Tonsils and adenoids of 67 children aged 2-16 years (mean 5.9 years) were divided into three groups: recurrent tonsillitis (n = 21), recurrent tonsillitis with tonsillar hypertrophy (n = 21) and tonsillar hypertrophy without history of tonsillitis (n = 25). The following biological markers were studied: anti-streptolysin O antibody and anti-deoxy ribonuclease B antibody serology, microbiology and cell count of granulocytes in tonsils and adenoids as well as lymphocyte subsets and "ex vivo" endonuclease activity in tonsils. Anti-streptolysin O antibody and anti-deoxyribonuclease B antibody titres were significantly raised in recurrent tonsillitis. Positive bacterial cultures for Streptococcus pyogenes were rare in cases of tonsillar hypertrophy. T-lymphocytes counts were lower and the proportion of basophils was higher in hypertrophic tonsils than in recurrent tonsillitis. Two parameters of apoptosis were studied; the activation of endonuclease, inducing breakdown of DNA resulting in cell death, and the sensitivity to thapsigargin, known to trigger the cleavage of DNA by apoptotic endonuclease. In children with tonsillar hypertrophy both parameters were decreased contrasting with those with recurrent tonsillitis where apoptosis is increased. It may be speculated that the increase of basophils in children with tonsillar hypertrophy results in increased release of interleukin-4, which could prevent lymphoid apoptosis and lead to cell proliferation in tonsillar tissue. CONCLUSION: Whereas recurrent tonsillitis is characterised by apoptotic death of lymphoid tissue, tonsillar hypertrophy is caused by environmental pollution agents that trigger the chronic inflammatory process without apoptotic cell death.

Apoptosis↗
PubMed1999

The oxidation-reduction state of serum proteins in multiple sclerosis patients: effect of interferon beta-1b.

The concentration of reduction equivalents in serum was studied in a cohort of healthy individuals, in a group of multiple sclerosis (MS) patients undergoing treatment with interferon beta-1b and another group of MS patients who refused treatment with interferon beta-1b. Two classes of sulfhydryl groups were detectable in serum: (1) the uncovered sulfhydryls, accessible to the oxidation-reduction substrate 5,5-dithiobis-(-2-nitrobenzoic acid) (DTNB); and (2) the hidden sulfhydryls that required previous heat denaturation of serum proteins to become accessible to DTNB. The concentration of the reduced form of both the uncovered- and hidden-type of sulfhydryls was higher in the serum of MS patients than in healthy individuals. Interferon beta-1b lowered the plasma concentration of the uncovered reduced sulfhydryls after 3 months of treatment. This was in contrast to a minor effect of interferon beta-1b in the hidden-form of sulfhydryl groups. The results suggest that the concentration of reduced sulfhydryls is a biochemical marker of the in vivo oxidation/reduction reactions in MS.

Adult↗
PubMed1999

Aminoglycosides activate oxygen metabolites production in the cochlea of mature and developing rats.

The ototoxicity of antibiotics, particularly of aminoglycosides, is a well-known undesirable side effect which may be based on a free radical mechanism. We studied the effect of different antibiotics in the production of reactive oxygen species in freshly isolated cochleas of mature and 2-10 weeks old developing rats. Phorbol myristate acetate induced the release of reactive oxygen species after a lag time close to 30 s and declined back to basal values in 10-20 min. The rate of reactive oxygen species production correlated inversely to the age in 2-10 weeks old rats. The study of a set of antibiotics showed that a very low concentration of gentamicin and streptomycin (10-100 ng/ml) enhanced the effect of phorbol myristate acetate. At the above-indicated concentrations, ciprofloxacin did not modify phorbol myristate acetate-induced activation. These results show the enhancement by aminoglycosides of reactive oxygen species production in cochlear tissues, particularly in developing rats.

Aging↗
PubMed1999

Visceral protein status and caloric intake in exercising versus nonexercising individuals with end-stage renal disease.

OBJECTIVE: To determine if differences exist in kilocalorie and protein intake and visceral protein levels for patients with End-Stage Renal Disease (ESRD) exercising during dialysis versus not exercising. DESIGN: Prospective study of 11 patients with ESRD over a study period of 12 weeks. SETTING: Outpatient renal dialysis clinic. PATIENTS: Patients with ESRD undergoing hemodialysis (HD) three times weekly who met the following criteria were selected: aged 25 to 65 years, nondiabetic, no current physical activity, blood pressure of 160/95 mm Hg or less at the second hour of HD, no unstable angina pectoris. Eleven patients who met the criteria were randomized into two groups; five patients with exercise (E) and six patients without exercise (NE). INTERVENTIONS: From weeks 5 to 8, E patients began exercise during HD three times a week. Exercise gradually increased by 3 minutes each dialysis day, maintaining 60% to 80% maximal heart rate (HR). By the end of week 8, all E patients reached 45 minutes of exercise, including 5 minutes each of warm-up and cooldown. Patients continued 45 minutes of exercise each dialysis day during HD at 60% to 80% maximal HR during weeks 9 through 12. NE patients remained sedentary throughout the study. MAIN OUTCOME MEASURE: Twenty-four-hour dietary recalls were obtained weekly for the 12 weeks from all patients for kilocalorie and protein intake. Serum levels of prealbumin, transferrin, and predialysis and postdialysis albumin were obtained immediately before the study onset and at weeks 4, 8, and 12. Comments related to patients' feelings and exercise were recorded but not analyzed statistically. RESULTS: Analysis of covariance for repeated measures for kilocalories yielded no significance by group or over time. Mean intakes for E patients for weeks 9 through 12 were clinically greater than weeks 1 through 8 by approximately 200 kilocalories. The mean protein intake for E patients at weeks 9 through 12 (79 +/- 41 g) appeared clinically greater than NE patients at weeks 9 through 12 (58 +/- 11 g), although not statistically different. Adequacy of dialysis (Kt/V) and initial levels of each serum protein were covariates for analysis of variance. No statistical differences were found for prealbumin levels. Transferrin levels were within normal ranges but differed (P <.05) by group (E or NE) and time periods. Prealbumin and postalbumin concentrations ranged from slightly low to adequate levels and were different over time (P <. 05). CONCLUSION: Kilocalorie and protein intakes appeared to increase for E patients during the exercise program. No consistent increases of visceral proteins were found for E patients. A majority of E patients expressed feelings of improved health, better exercise tolerance, and improved appetite and viewed exercise as enjoyable.

Adult↗
PubMed1999

The beta enolase subunit displays three different patterns of microheterogeneity in human striated muscle.

In higher vertebrates, the glycolytic enzyme enolase (2-phospho-D-glycerate hydrolyase; EC 4.2.1.11) is active as a dimeric protein formed from three subunits--alpha: ubiquitous, beta: muscle specific, and gamma: neuron specific--encoded by different genes. In the present study, we have shown that an antiserum previously produced against the mouse beta beta enolase is also a specific reagent for the muscle specific human enolase. Using this antiserum to study human muscles, we demonstrated novel patterns of the beta subunit microheterogeneity which are distinctive from those observed previously in rodents and which appear to be independent of age, gender and muscular activity. Two variants of the beta subunit differing by their size have been detected: one heavy form of 46 kDa (beta H) and one light form of 45 kDa (beta L). Muscle biopsies expressed either beta H or beta L or beta H + beta L, and all muscles of an individual expressed the same variants. The products of in vitro translation of RNA prepared from human muscle displayed beta subunit variants identical to those of the protein present in the biopsy. Therefore the differences observed between individuals reveal a difference already present at the level of the RNA transcripts. These observations suggest the existence of an yet undescribed polymorphism of the human beta enolase gene which could affect the coding sequence. Comparative immunocytochemical and histochemical analyses of biopsies demonstrated that the beta subunit was expressed in all fast fibres (type II), but not in slow fibres (type I). No difference was observed in the intensity of beta enolase immunolabelling between the various types (IIA, IIAB, IIB) of fast fibres. No significant difference in fibre type composition and histological appearance was visible between muscles presenting either one of the three patterns of microheterogeneity.

Adult↗
PubMed1999

Denervation of rabbit gastrocnemius and soleus muscles: effect on muscle-specific enolase.

We report here, for the first time, the expression of the muscle-specific isoform of the glycolytic enzyme, enolase (EC 4.2.1. 11) (beta enolase), in rabbit skeletal muscles. We have analysed the fast-twitch gastrocnemius and the slow-twitch soleus muscles during normal postnatal development and following denervation. We show that, in rabbit, as already described in rodents, beta enolase gene expression behaves as a good marker of the fast-twitch fibers. In soleus muscle, the beta enolase transcript level is 10-20% of that found in gastrocnemius. Denervation, performed at 8 postnatal days, induces an important drop of beta enolase transcript levels in both developing soleus and gastrocnemius muscles, with a 80% decrease observed 1 week after denervation in the operated muscles, as compared to the corresponding contralateral muscles. Thereafter, the beta enolase transcript level continues to decrease in the fast-twitch muscle, with the beta enolase subunit being detectable only in the atrophic fast-twitch fibers. In contrast, the beta transcript level tends to increase in the denervated slow-twitch muscle, reaching about 50% of that in contralateral soleus, at 7 weeks after surgery. The level of beta enolase transcripts still expressed after denervation seems to stabilize at the same low level in both types of inactive muscles. This suggests that the small fraction of beta enolase expression which is not controlled by the nerve, or by the contractile activity imposed by it, is independent of the muscle phenotype.

Animals↗
PubMed1999

Autoimmune deafness is not related to hyperreactivity to type II collagen.

The pathogenic role of anti-type II collagen was analysed in a variety of hearing losses, in age-matched controls and in different autoimmune diseases. The immune reactivity of peripheral blood lymphocytes to type II collagen was studied by the degree of proliferation measured as the incorporation of bromodeoxyuridine in cultured lymphocytes. The anti-type II collagen antibodies showed a very low incidence in the hearing loss group. Lymphocytes of otosclerosis, Meniere's disease and other sensorineural deafness patients proliferated in response to concanavalin A and to type II collagen to a lower extent than peripheral blood lymphocytes from healthy controls. Nonetheless, these differences were not statistically significant. The immune hyperreactivity to type II collagen cannot explain the autoimmune mechanism of hearing losses. Humoral and cellular hyperreactivities to inner ear proteins different from type II collagen, could explain the autoimmune mechanism of deafness.

Adolescent↗
PubMed1999

SF-36 scores vary by method of administration: implications for study design.

BACKGROUND: Previous research suggests that people respond differently to health status measures when data are collected by interview or self completion of a questionnaire. The objective of this study was to determine whether SF-36 health status scores differ systematically by method of administration. METHOD: A randomized cross-over study was carried out on 210 new attenders at general medicine, endocrinology, gastroenterology and urological out-patient departments. The outcome was the difference in SF-36 profiles comparing clinic based interviews with self completion at home by the same subjects. RESULTS: For seven of the eight variables of the SF-36 scores were lower in the self assessment, the differences being statistically significant in four of the eight comparisons. The largest differences were in role limitations due to emotional problems (difference 14.74, 95 per cent confidence interval (CI) 7.76-21.7) and social function (difference 7.21, 95 per cent CI 3.19-11.23). CONCLUSIONS: Clinic based interviews systematically exaggerate health status compared with self assessment. The difference is sufficiently large to underestimate the effectiveness of health service interventions when a clinic based pre-intervention and postal self completed follow-up design is used, unless adjustment is made for this systematic bias.

Analysis of Variance↗
PubMed1999

Context effects in lexical access: a meta-analysis.

The modularity hypothesis was evaluated in this review of 25 studies that investigated context effects in early lexical processing. Selection criteria restricted the review to priming studies and to studies that presented the target word before or at the end of the prime word. Meta-analysis was used to provide summary information about the 17 studies in the review for which effect sizes could be calculated. Overall, the analysis revealed a small effect of context on lexical access. Results provide a disconfirmation of the modularity hypothesis; although multiple interpretations of a word were sometimes accessed, the contextually appropriate interpretation was consistently more strongly activated. The lack of significant heterogeneity of variance suggests that the variability observed across studies was due to sampling error; however, task, timing of target presentation, meaning frequency, type of target, and type of context were identified as potential moderator variables.

Humans↗
PubMed1999

Utilisation of predictive, prenatal and diagnostic testing for Huntington's disease in Johannesburg.

CONTEXT: Huntington's disease (HD) is a dominantly inherited condition in which the gene defect is known. As such individuals in at-risk families can be tested before symptoms occur, prenatally, or after symptoms appear to confirm the diagnosis. OBJECTIVES: To investigate the utilisation and sequelae of the predictive, prenatal and diagnostic services offered to families with suspected Huntington's disease. DESIGN: A retrospective design was used. The 1975-1997 records of the Department of Human Genetics for all families with a history of HD presenting for genetic counselling and DNA analysis were studied. SETTING: Department of Human Genetics, South African Institute for Medical Research and University of the Witwatersrand, Johannesburg. SUBJECTS: There were 30 at-risk (50% risk) subjects for predictive testing, 7 women (10 pregnancies) for prenatal testing, and 52 subjects for diagnostic testing. OUTCOME MEASURES: These were provided by the results from molecular studies and by the action taken by subjects after a predictive or prenatal result was given. RESULTS: Altogether 15 (50%) subjects for predictive testing had a positive result, but none had serious psychiatric sequelae. Two women were found to be carrying an affected fetus and both requested pregnancy termination. Of 52 diagnostic tests, 33 (63%) were positive. CONCLUSION: The service was used appropriately, and there were no traumatic incidents following positive results. There was no genotypic or sex bias in subjects presenting for testing. Black and white patients were equally likely to be positive for HD on diagnostic testing. The families appreciated the service and found it useful in the detection and prevention of HD.

Female↗